Silver halide emulsion containing a mercapto pyrimidine derivative antifoggant

ABSTRACT

THE STABILITY IN STORAGE AND DEVELOPMENT OF SILVER HALIDE EMULSION LAYERS GAINST DEFORMATION OF UNIFORM FOG IS IMPROVED BY THE ADDITION OF MERCAPTO PYRIMIDINE DERIVATIVES AS ANTIFOGGANTS.

United States Patent 3,692,527 SILVER HALIDE EMULSION CONTAINING A MERCAPTO PYRIMIDINE DERIVATIVE ANTI- FOGGANT Anita von Kiinig and Hans-Joachim Kabbe, Leverkusen, Helmut Miider, Odenthal-Hahnenberg, and Rigobert Otto and Helmut Reuss, Leverkusen, Germany, assignors to Agfa-Gevaert Aktiengesellschaft, Leverkusen, Germany No Drawing. Filed Dec. 4, 1970, Ser. No. 95,401 Claims priority, application Germany, Dec. 13, 1969, P 19 62 605.2 Int. Cl. G03c 1/34 US. Cl. 96109 4 Claims ABSTRACT OF THE DISCLOSURE The stability in storage and development of silver halide emulsion layers against deformation of uniform fog is improved by the addition of mercapto pyrimidine derivatives asuantifoggants.

The invention relates to a photographic material comprising at least one silver halide emulsion layer whose stability in storage and development has been improved by means of the addition of pyrimidine derivatives.

It is well known that light-sensitive silver halide emulsions, especially those which have been chemically sensitized, have a tendency to fog, that is to say to the formation of nuclei which are capable of development without exposure to light. Fogging occurs if the photographic material has been stored too long, especially at elevated temperature and atmospheric moisture, or if the emulsions have been overripened or the materials are subjected to high mechanical stresses.

Additional fogging may also occur during development itself, due to the use of contaminated or very much used developers or if development is carried on for too long or at extremely high temperatures. In many cases, the formation of fog during storage can be delayed by storing the photographic material at low temperature and at relatively low humidity. However, photographic materials often have to be stored and developed under adverse conditions, e.g. in the tropics where both high relative humidity and high temperatures prevail.

To a certain extent, the tendency of the photographic silver halide emulsions to fog can be suppressed by the addition of so-called stabilizers or antifoggants. Substances which have this effect are, for example, heterocyclic mercapto compounds or organic mercury compounds.

While treatment with antifoggants may, in some cases, control the fog levels, certain antifoggants reduce at their effective concentrations rather severely the speed of the stabilized emulsion, thus reducing its usefulness. The gradation of the emulsion may also be adversely aflected by antifoggants.

It is among the objects of the invention to provide antifoggants which cause little or no reduction in sensitivity at a concentration which is sufficient to efiect stabilization. Another object of the invention is the preparation of photographic emulsions which are stabilized with these agents.

We now have found a photographic material having at least one silver halide emulsion layer stabilized with a ice pyrimidine derivative which contains, as stabilizer, a 2- mercapto-4-keto-3,4-dihydropyrirnidine derivative having at least one carboxy or sulfo group of the following formula:

0 II c ,0 \N-R N -C\ /CSH wherein R represents hydrogen, a saturated or olefinically unsaturated aliphatic group having preferably up to 12 carbon atoms or aryl, preferably a ring of the phenyl series, and

stands for the ring members required for completing a condensed carbocyclic ring of the benzene series, the cyclopentene series or the cyclohexene series, or a condensed heterocyclic ring selected from the following group: pyridine, tetrahydropyridine, pyrimidine, pyrrole, furan, thiophene, oxazole, isooxazole, imidazole or pyrazole. The condensed carbocyclic or heterocyclic ring may carry further substituents, e.g. saturated or olefinically unsaturated aliphatic groups having 1 to 18 and preferably up to 5 carbon atoms, phenyl, haolgen such as chlorine or bromine, hydroxyl or alkoxy. Either the condensed carbocyclic or heterocyclic ring or an aliphatic or aromatic group attached to it or the substituent R contains at least one carboxyl or sulfonic acid group.

Particular utility is exhibited by the following compounds:

N-[CHzlur-COOH CH2C O OH.

The compounds to be used according to the invention may be prepared by methods which are known in principle. Thus the pyrimidine ring may be obtained by reacting an amine with an ortho-alkoxycarbonylisothiocyanate or by reacting an isothiocyanate with an orthoaminocarboxylic acid derivative. Furthermore, the 4-mercapto group in 2,4-dimercaptopyrimidine derivatives may be replaced by the 4-keto group. In all these reactions, the carboxyl groups present in the end products may also be introduced as their derivatives such as esters, amides or nitriles from which they are liberated by saponification.

The preparation of the compounds shown in the above table will now be described.

Compound 1 I 166 g. of 2,4-dimercapto-6-cyanoquina1oline are dissolved in a sodium hydroxide solution prepared from 165 g. of sodium hydroxide and 600 m1. of water, and heated at 95 C. to 100 C. for 10 hours. This solution is then diluted with l l. of water, stirred up with active charcoal, filtered and acidified with 3 N HCl. The precipitate is suction filtered, dried and recrystallized from dimethyl formamide/water. Yield: 144 g. (86%) of 2 mercapto- 4 keto 3,4 dihydroquinazoline carboxylic acid (6); M.P. 345 C.

Compound 2 g. of l-(rn-carboxyphenyl) 4,6 dimercapto-pyrazolo-[3,4-d]-pyrimidine are heated at reflux temperature in 100 ml. of 4 N NaOH for 10 hours. The reaction mixture is then diluted with 200 ml. of water, acidified with dilute HCI, filtered under suction and recrystallized from dimethyl formamide/water. Yield of 1-(m-carboxyphenyl)-4-keto-6-mercapto 4,5 dihydropyrazolo [3,4-d]- pyrimidine: 13 g. (69%), M.P. 189 C. to 191 C.

4 Compound 3 25 g. of 2- ethoxycarbonyl-3-methy1-4,6-dimercaptothiopheno-[2,3-d]-pyrimidine are heated at reflux temperature in 250 m1. of 2 N NaOH for 10 hours. After working up the product in the same Way as in Example 2, 16.5 g. (79%) of 2-carboxy-3-methyl-4-keto-4,5-dihydro 6 mercapto-thiophene-[2,3-d]-pyrimidine are obtained. M.P. 285 C. to 287 C.

Compound 4 12.5 g. of the sodium salt of "y-aminobutyric acid are dissolved in 25 ml. of dimethylformamide/ 8 ml. of water, and 20 g. of o-ethoxycarbonylphenylisothiocyanate in 50 ml. of toluene are then added in one portion, the mixture heating up to C. as a result of this addition. The reaction mixture is then stirred for 30 minutes at C., diluted with ml. of water and acidified with acetic acid. The resulting precipitate is recrystallized from dimethyl formamide/rnethanol. Yield of 'y-[3-(2-rnercapto- 3,4-dihydro 4 keto-quinazolinyl) ]-butyric acid: 20 g. (76%), M.P. 221 C. to 223 C.

Compound 5 The method employed is the same as in Example 4 but using 18 g. of the sodium salt of p-a-minobenzoic acid. Yield of p-[3-(2-mercapto-3,4-dihydro-4-keto-quinazolinyl)]-benzoic acid: 19 g. v(62%), M.P. 342 C.

Compound 6 The method employed is the same as in Example 4 but using 19.5 g. of the sodium salt of sulfanilic acid. Yield of p [3-(2-mercapto-3,4-dihydro-4-keto-quinazolinyl)]- benzene sulfonic acid: 15 g. (42%), M.P. 350 C.

Compound 7 The method employed is the same as in Example 4 but using 15.3 g. of the sodium salt of fi-aminocaproic acid. Yield of 6- 3- Z-mercapto-3,4-dihydro-4-keto-quinazolinyl)]-caproic acid: 20 g. (70%), M.P. 210 C.

Compound 8 The method employed is the same as in Example 4 but using w-amino-decan carboxylic acid. Yield of w-[3-(2- mercapto 3,4 dihydro-4-keto-quinazo1inyl)J-decancarboxylic acid: (51%), M.P. 132 C.

Compound 9 The method employed is the same as in Example 5, but using 18 g. of the sodium salt of anthranilic acid. Yield of o-[3-(2-mercapto 3,4 dihydro-4-keto-quinazolinyl) benzoic acid: 23 g. (77%), M.P. 133 C.

Compound 10 The method employed is the same as in Example 4 but using the sodium salt of amino acetic acid. Yield of 3-(2- mercapto 3,4 dihydro-4-keto-quinazolinyl)-acetic acid: (82%), M.P. 288 C.

The stabilizers according to the invention are advantageously added to the light-sensitive silver halide emulsions after chemical ripening although they may, of course, also be added to other photographic layers. The concentration of the stabilizers in the emulsion may vary within wide limits. It depends on the nature of the emulsion and the effect required. The required effects are generally obtained with quantities of 1 mg. to 1 g. per mol of silver halide. The quantities used for black and white emulsions are preferably 100 to 500 mg. per mol of silver halide and the quantities used for emulsions which contain color couplers are preferably 5 to 100 mg. of stabilizer per mol of silver halide. The optimum quantity to be added to any given emulsion can easily be determined by the usual tests.

The stabilizers according to the invention may be used in any silver halide emulsions. Suitable silver halides are silver chloride, silver bromide or mixtures thereof, optionally with a small silver iodide content of up to mols percent. The silver halides may be dispersed in the usual hydrophilic compounds, for example carboxymethyl-cellulose, alkyl cellulose, hydroxyethylcellulose, starch or its derivatives, carrageenates, polyvinyl alcohol, polyvinylpyrrolidone, alginic acid and its salts, esters or amides and preferably gelatin.

The emulsions may be chemically sensitized in the usual manner, for example with salts of noble metals such as ruthenium, rhodium, palladium, iridium or platinum. They may also be sensitized with gold salts as described in the article by R. Koslowsky, Z. Wiss. Phot. 46, 65-72 1951).

The emulsions may also be chemically sensitized, e.g. by the addition of compounds which contain sulfur during chemical ripening, for example allylisothiocyanate, allyl thiourea, sodium thiosulfate or the like. Reducing agents, e.g. the tin compounds described in Belgian Pats. Nos. 493,464 and 568,687, or polyamines such as diethylene triamine or aminomethylsulfinic acid derivatives, e.g. those mentioned in Belgian Pat. No. 547,323, may also be used as chemical sensitizers.

The emulsions may also be sensitized with polyalkylene oxide derivatives, e.g. with polyethylene oxide having a molecular weight of between 1000 and 20,000, with condensation products of alkylene oxides and aliphatic alcohols or glycols or cyclic dehydration products of hexitols, or with alkyl substituted phenols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides. The condensation products have a molecular weight of at least 700 and preferably more than 1000. These sensitizers may, of course, also be combined in order to achieve special effects, as described in Belgian Pat. No. 537,278 and in British Pat. No. 727,982.

The emulsions may also be optically sensitized, e.g. with the usual polymethine dyes such as neutrocyanines, basic or acid carbocyanines, rhodacyanines, hemicyanines, styryl dyes, oxonoles and the like. Sensitizers of this type have been described in the work by F. M. Hamer The Cyanine Dyes and related Compounds (1964).

The emulsions may be hardened in the usual manner, for example With formaldehyde or halosubstituted aldehydes which contain a carboxyl group, such as mucobromic acid, diketones, methanesulfonic acid esters, dialdehydes and the like.

The silver halide emulsions according to the invention may contain other stabilizers in addition, preferably tetraor penta-azaindenes and especially those which are substituted with hydroxyl or amino groups. Compounds of this type have been described in the article by Birr in Zeitschrift fiir Wissenschaftliche Photographic, volume 47, 1952, page 2 to 28. The emulsions may also contain heterocyclic mercapto compounds such as mercapto tetrazoles or mercury compounds as stabilizers.

The pyrimidine stabilizers to be used according to the invention are especially advantageous in their effect in silver halide emulsions which contain color couplers. The presence of the color couplers often severely reduces the effect of known stabilizers so that in the case of such emulsions it is especially difiicult to achieve satisfactory stability in storage or sufiicient freedom frem fogging if development is carried out for a long time or at high temperatures. The formation of color fog is practically completely suppressed by the pyrimidine derivatives described here. These stabilizers are especially effective in the rapid processing of color photographic materials, in which development is carried out at elevated temperatures.

Moreover, the pyrimidine derivatives used according to the invention have much less effect on the sensitivity of the photographic emulsions used than the known heterocyclic mercapto compounds used for this purpose. Even the sensitivity of the most highly sensitive silver halide emulsions is not substantially reduced by the present stabilizers.

6 EXAMPLE 1 300 ml. of a 6% aqueous alkaline solution of the following cyan coupler:

are added to 1 kg. of a red sensitized photographic silver bromide emulsion which contains g. of gelatine and 0.4 mol of silver bromide. The emulsion in addition contains 50 ml. of a 1% methanolic solution of 4-hydroxy-6- methyl-1,3,3a,7-tetraazaindene, 30 ml. of a 10% aqueous saponin solution and 15 ml. of a 0.5% aqueous chrome acetate solution.

The compounds according to the invention are added in the quantities indicated below, in each case in the form of 0.1% solutions in methanol:

Ml. Compound 1 20 Compound 2 50 Compound 3 50 Compound 4 50 Compound 5 50 Compound 6 20 The control sample does not contain any additional stabilizer. The 7 samples are applied to a layer support of celluose triacetate in a thickness of about 45,14. The pH of the casting solution is adjusted to 6.7.

After drying, the film is exposed in a conventional sensitometer behind a stepless grey Wedge and the samples are processed separately in two different developers.

Developer 1 2.75 g. of N,N-diethyl-p-phenylenediaminosulfate 1.2 g. of hydroxylamine hydrochloride 2 g. of sodium sulfite sicc.

2 g. of sodium metaphosphate 75 g. of potassium carbonate 2 g. of potassium bromide Water up to 1 l.

The development times are 15 minutes for developer 1 and 8, 12 and 16 minutes for developer 2.

The samples developed in developer 1 are then treated as follows:

Short stop bath (4 minutes): 17 ml. of glacial acetic acid;

2.94 g. of sodium acetate sicc.; water up to 1 l.

Hardening bath (4 minutes): 0.32 g. of sodium hydroxide; 0.5 g. of sodium hexametaphosphate; 9.04 g. of soda; 20 ml. of Formalin; water up to l 1.

Washing (5 minutes), bleaching bath (6 minutes): 6 g. of sodium hexametaphosphate; 42 g. of potassium ferricyanide; 12 g. of potassium bromide; 6 g. of disodium phosphate; 16 g. of monopotassium phosphate; water up to 1 1.

Washing (5 minutes), fixing bath (8 minutes): g. of ammonium thiosulfate; 10 g. of sodium sulfite; water up to 1 1.

Washing (10 minutes), final bath (30 seconds): 0.3 g. of sodium tetrapropylene benzene sulfate; water up to 1 l.

The densitometric determination shows that all the 7 samples have practically the same sensitivity. The fog values are summarized in the following table:

Additive: Fog Compound 1 0.18 Compound 2 0.18 Compound 3 0.20 Compound 4 0.19 Compound 5 0.16 Compound 6 0.14 Control 0.31

The samples processed in developer 2 are then treated as follows:

Washing (15 minutes), bleaching bath (5 minutes): 3 g. of ethylenediaminotetraacetic acid; 50 g. of potassium ferricyanide; 15 g. of potassium bromide; l g. of disodium phosphate; 10 g. of monopotassium phosphate; Water up to 1 1.

Washing (5 minutes), fixing bath (5 minutes): 200 g. of

sodium thiosulfate; water up to 1 1.

Washing (10 minutes).

The fog values summarized in the following table are obtained with practically the same sensitivity in the individual samples:

Fog values after thte following develop- An emulsion is prepared in the same way as in Example 1 but it is green sensitized, and instead of the cyan coupler it contains, per kg, 300 ml. of a 2.5% solution of the following magenta coupler in aqueous NaOH solution:

The emulsion is divided into 4 parts, and the following compounds, in each case in the form of a 0.1% solution in methanol, are added to three of these parts:

Ml. Compound 1 5 Compound 2 10 Compound 4 10 The emulsions are exposed in a conventional sensitometer behind a grey stepless test wedge and developed for 8 minutes in developer 2 according to Example 1. The samples are then treated as described in Example 1 for the samples processed in developer 2.

The results of the sensitometric test show practically the same sensitivity in all the emulsions. The fog values are summarized in the following table:

EXAMPLE 3 An unwashed silver chlorobromide gelatine emulsion (20 mol percent of AgBr) which contains 0.18 mol of silver halide per litre is applied to a layer support of baryta paper in a known manner after the addition of 20 ml. of a 10% aqueous saponin solution and 2 ml. of a 30% aqueous Formalin solution, and dried. The amount of silver applied is 1.5 to 1.6 g./m.

The emulsion mentioned above is divided into several parts before being casting. The stabilizers are added to these parts in the form of a 1%} solution in dimethylformamide. The quantities added are shown in the table here inafter.

The samples were developed fresh and after 48 hours storage in a heating cupboard at C. and 40% relative humidity, using a developer of the following composition:

1 g. of p-methylaminophenol-sulfate 3 g. of hydroquinone 13 g. of sodium sulfite sicc.

26 g. of sodium carbonate sicc.

1 g. of potassium bromide Made up to 1 l. with water.

for 2, 4 and 6 minutes at a temperature of 30 C. The grey fog of the various materials was measured with a densitometer and the following results were obtained:

A washed silver bromide gelatine emulsion containing 0.16 mol of silver bromide per litre is applied to a support of baryta-coated paper in a known manner after the addition of the casting additives mentioned in Example 1 and dried. The amount of silver applied is 1.7 to 1.8 g./m. The emulsion indicated above is divided into several parts, and the stabilizers are added as indicated in Example 3. The papers are processed as in Example 3 and the following results are obtained:

Fog

Fresh sample Heating cupboard develsample development Concenopment time oftime tration, Compound No. mg./l. 2min. 4min. 6min. 2min. 4min. 6min Control sample--- 0 0.12 0.19 0.26 0 14 0.19 0.26 4 30 0.09 0.11 0.13 0 10 0.13 0.14 30 0.09 0.11 0.12 0.09 0.11 0.12 30 0.09 0.10 0.11 0.08 0.11 0.13

We claim: 1. A light-sensitive photographic material having at least one silver halide emulsion layer containing therein 9 an antifogging concentration of a mercapto substituted pyrimidine derivative of the following formula:

in which R=hydrogen, a saturated or olefinically unsaturated aliphatic group or aryl;

Z1=the ring members required for completing a condensed benzene, cyclopentene or cyclohexene ring or a heterocyclic ring selected from the following group pyridine, tetrahydropyridine, pyrimidine, pyrrol'e, furan, thiophene, oxazole, isooxazole, imidazole or pyrazole ring; R or Z contains at least one carboxyl or sulfo group.

5 ring members required for completing a benzene ring.

4. The material of claim 1, wherein the silver halide emulsion layer contain a color coupler.

References Cited UNITED STATES PATENTS 2,772,164 11/1956 Allen et al. 96-l09 3,202,512 8/1965 Williams 96-l09 r NORMAN G. TORCHIN, Primary Examiner W. H. LOUIE, JR., Assistant Examiner US. Cl. X.R. 96-400 

